Electronic Design

Power MOSFETs Switch High-Side Load Intelligently

Tapping an advanced CMOS process and innovative circuit design, Advanced Analogic Technologies has readied a family of intelligent power control switches for cell phones, PDAs, and other portable consumer electronics.

Built around p-channel power MOSFETs with very low on-resistance, the Smart-Switches integrate a variety of protection and interface functions on a single CMOS die. There are two versions in this line. While the current-limiting model controls external loads with either fixed or adjustable limits, the slew-rate-controlled version controls internal loads.

The current-limiting AAT4618 is a p-channel MOSFET power switch that operates over a 2.4- to 5.5-V input range. Designed for high-side load switching, it offers ultra-fast transient response with overtemperature protection. Its current-limit response to a short circuit is rated at 400 ns. The device can control loads that require up to 500 mA. Typical quiescent current is 10 µA, and the supply current drops to 1 µA in shutdown mode.

Designed for inrush-limiting applications, the slew-rate-controlled AAT4250 and AAT4280 power switches operate over a 1.8- to 5.5-V input range. Quiescent current for both is 2.5 µA. They also offer undervoltage lock-out. While the AAT4250 features 1.5-ms turn-on and 10-µs turn-off, the AAT4280 comes in three flavors of turn-on and turn-off characteristics.

The AAT4280(-1) is functionally compatible with the 4250 but with better RDS(ON) characteristics. The AAT4280(-2) offers less than 210-ns turn-on and 3-µs turn-off, and the AAT4280(-3) features a shutdown load discharge circuit to rapidly turn off a load when the switch is disabled.

The AAT4618 and AAT4250 are available in five-pin SOT-23 and eight-pin SC70JW packages. The AAT4280 is available in a six-lead SOT-23 and an eight-lead SC70JW. In 1000-piece lots, the AAT4618 costs $0.39, and the AAT4250 and AAT4280 cost $0.32 and $0.44, respectively.

Advanced Analogic Technologies Inc. www.analogictech.com; (408) 524-9684.

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